Tuesday, June 24, 2014

Woven Fabrics

Today we're going to discuss woven fabrics, and how they're constructed. Woven textiles have very little to no stretch built into their structure. The lengthwise threads of woven fabric are called the warp, and the crosswise threads are the weft. The weft is woven through the warp, and the warp is what gets wrapped around the bolt.

You can create your own example fabric at home, using some paper, scissors, and tape! It helps if at least one sheet of paper has some colour, but if you only have white printer paper around, you can scribble on one with a marker or pen, or do something to make two of the sheets different from one another.

1. Take one of the two coloured pieces of paper, and fold it in half lengthwise. Without unfolding, fold it in half three more times. Unfold it, and cut along the creases, you should have 16 strips just over half an inch wide.

I cut up some scrapbook paper sheets I had laying around:

2. Take eight strips and tape them to the third piece of paper. These are going to be your warp "threads".

3. Take one strip of the other colour and cut it in half. Then, lift every even numbered warp thread, and slide a half strip in. Do this a few times, and you have an example of plain weave fabric.

This is the basis of most fabrics you would use when you start sewing. Muslin, broadcloth, and quilting cotton all tend to be plain weave, and is the easiest to handle.
Fabric on the bolt, however, is made with very long weft threads. The edges of your fabric, referred to as selvage, is where the weft threads wrap. You can simulate this by taping multiple strips together, and then folding it a bit to weave the next row:

It isn't pretty, and obviously paper is not as flexible as threads, but it's a great way to understand how your fabric is created. If you cut the warp threads, as you would when you buy a piece off the bolt, you can see how easy it is for the weft threads to unravel. This is why it's important to bind your fabric edges when you're sewing a garment, either by doing a zig-zag stitch or using a serger.

Plain weave isn't the only type of weave out there, however! Other important types of weaves are twill and satin. Here are some examples.This is 2/2 twill. That means my weft threads go over two warp threads, then under the next two. But in the next row, I shift the entire pattern over. This is what creates the diagonal pattern you can see below. Twill weave is stronger than plain weave, and you can see a twill variation in pretty much any piece of denim. Look closely at your jeans some time, and you will likely see a twill weave of some sort.

This is 3/1 satin. In this case, my weft threads go over one warp thread, then under the next three. Like the twill weave, the pattern gets shifted for each subsequent row, and we also have a diagonal pattern, only this time the warp threads are above the weft threads for more rows. This is what gives satins and sateens that smooth feeling, because there are fewer interruptions in the threads.

How the threads are woven determine the type of fabric, and also how the fabric behaves in different situations. This is why it's important to find the right fabric for the project you want to work on.

If you have leftover strips, save them for the next discussion, on knit fabrics, or make some stars: